Fuel Cells Flashcards
(13 cards)
Are fuel cells a clean source of energy?
When only considering the exhaust gas themselves, they are a clean source as it is mainly just water exhausted.
When looking at the whole process of creating these fuel cells, they have a decent sized eco footprint, unless hydrogen is a byproduct of your plant and you can utilize your waste.
what is the fundamental operation of a fuel cell
- hydrogen diffuses the porous anode and oxidizes (losing an electron), becoming an H+ ion
- electrons flow through external and recombine with H+ ion from the electrode
- hydrogen atoms then combine with O2 to form the product H2O
what does the overall reaction look like?
chemical reaction equation
H2 + 0.5 O2 -> H2O + heat (HV)
where does the O2 come from explain when you would not use this primary source of O2?
- O2 comes from natural Air
- you would not use natural air when your system is sensitive to carbon
what do the number of cells in a stack represent
voltage potential
1 cell = 1 V
what determines the current in a cell
the current is determined by the cell force area
-describes through current density [Amp/cm2]
How is a cell put together
- end plate
- anode
- electrolyte matrix
- cathode
- endplate or separator
what are the components of a simple fuel cell system
- fuel processing system
- oxidant conditioning
- electrolyte management
- thermal management
- reaction product removal
- power conditioning
- may include bottoming cycle
what is the theoretical efficiency of a hydrogen-water (liquid) system
82.97%
what is the theoretical efficiency of a hydrogen water gas system
94.5%
what is the theoretical efficiency of a methane-water liquid system
91.87%
what is the theoretical efficiency of a carbon gas system
1.24%
why might you see a thermal efficiency over 1
if a thermal efficiency if over 1 endothermic reactions may not have been considered or energy absorbed from surrounding areas
